Construction Machine

ABSTRACT

It is made possible to perform power reduction control during non-operation of control levers, suppress a return to a normal power state when a control lever is accidentally moved, and make a smooth transition to an operation desired to be performed when a return is made to the normal power state. To this end, in a power reduction state, when a first cancellation condition in which two or more control levers are inclined simultaneously is satisfied or when a second cancellation condition in which one lever continues to be inclined is satisfied, a controller  50  determines that an operator “has an intention of canceling power reduction” and cancels power reduction control.

TECHNICAL FIELD

The present invention relates to a construction machine such as a hydraulic excavator, and particularly to a construction machine that performs power reduction control of reducing power output by a power source during non-operation of control levers.

BACKGROUND ART

Patent Document 1, for example, describes a technology in which a construction machine performs power reduction control referred to as auto idle control, which reduces power output by an engine by reducing the rotation speed of the engine during non-operation of control levers.

In addition, Patent Document 2 and Patent Document 3, for example, describe technologies of performing authentication as a theft preventing device of a construction machine on the basis of an input pattern of the control levers.

PRIOR ART DOCUMENT Patent Documents

Patent Document 1: WO2018/179313

Patent Document 2: JP-1999-140918-A

Patent Document 3: JP-2018-016985-A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The construction machine that performs the power reduction control (auto idle control) of reducing the power output by the engine as a power source during the non-operation of the control levers as described in Patent Document 1 is generally enabled to return to a normal power state by canceling the power reduction control when the control levers are operated. However, when the power reduction control is performed in such a manner, the control may be canceled though the power reduction control is not intended to be canceled when a hand accidentally hits a control lever, for example.

The authentication technologies for the input pattern of the control levers as described in Patent Documents 2 and 3 may be applied as a solution to this problem. By applying such an authentication technology, it is possible to cancel the control and return to the normal power state only when the power reduction control is intended to be canceled.

However, in the case of this method, a smooth transition to an operation desired to be performed cannot be made when a return is made to the normal power state. For example, when a set recognition pattern is “inclining a lever for the right hand to the front direction and inclining a lever for the left hand to the front direction,” and the operation desired to be performed is “inclining the lever for the right hand to the rear direction and inclining the lever for the left hand to the right direction,” the control levers need to be returned to a neutral state after the control levers are once operated in the set operation pattern. Therefore, an operator cannot make a smooth transition to the operation desired to be performed.

The present invention has been made on the basis of the above-described problems. It is an object of the present invention to provide a construction machine that can perform power reduction control during non-operation of control levers, suppress a return to a normal power state when a control lever is accidentally moved, and make a smooth transition to an operation desired to be performed when a return is made to the normal power state.

Means for Solving the Problem

In order to solve such problems, according to the present invention, there is provided a construction machine including: a power source; a plurality of actuators that are actuated by receiving power output by the power source; a plurality of control levers that instruct amounts of the power to be distributed to the plurality of actuators; a plurality of operation state sensors that detect operation states of the plurality of control levers; and a controller that controls the power source, the plurality of control levers including a first control lever and a second control lever that operate different actuators of the plurality of actuators, the controller being configured to perform power reduction control of reducing the power when a non-operation state of the first and second control levers is continued, in which the controller is configured to cancel the power reduction control when a first cancellation condition in which the first and second control levers are operated simultaneously in a state in which the power is reduced is satisfied.

Advantages of the Invention

According to the present invention, while the power reduction control is performed during non-operation of the first and second control levers, the power reduction control can be canceled by merely operating the first and second control levers simultaneously in a power reduction state. Further, when one of the first and second control levers is accidentally operated, the power reduction control is not canceled, and thus a return to a normal power state can be suppressed. Furthermore, since the power reduction control is canceled by merely operating the first and second control levers simultaneously in the power reduction state, a smooth transition to an operation desired to be performed can be made at a time of a return to the normal power state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an external appearance of a construction machine (hydraulic excavator) in a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a driving system in the first embodiment.

FIG. 3 is a diagram of assistance in explaining movable directions of control levers of control lever devices in the first embodiment and definitions of the movable directions.

FIG. 4 is a diagram showing a configuration of an operation signal system of the driving system in the first embodiment.

FIG. 5 is a block diagram showing functions of a controller in the first embodiment.

FIG. 6 is a block diagram showing functions of a power computing section in the first embodiment.

FIG. 7 is a flowchart showing a computation flow of a first lever operation state determining section in the first embodiment.

FIG. 8 is a flowchart showing a computation flow of a second lever operation state determining section in the first embodiment.

FIG. 9 is a diagram showing relation between a sensor value and the meter-in opening area of a directional control valve in the first embodiment, and also showing a definition of a threshold value of operation pressure.

FIG. 10 is a flowchart showing a computation flow of a first lever operation time measuring section in the first embodiment.

FIG. 11 is a flowchart showing a computation flow of a second lever operation time measuring section in the first embodiment.

FIG. 12 is a flowchart showing a computation flow of a power reduction determining section in the first embodiment.

FIG. 13 is a timing diagram showing an example of changes in operation pressure and target rotation speed when the levers are operated in the first embodiment.

FIG. 14 is a block diagram showing functions of a power computing section of a controller in a modification of the first embodiment.

FIG. 15 is a flowchart showing a computation flow of a power reduction determining section in the modification of the first embodiment.

FIG. 16 is a diagram showing a configuration of a driving system in a second embodiment.

FIG. 17 is a block diagram showing functions of a controller in the second embodiment.

FIG. 18 is a block diagram showing functions of a power computing section in the second embodiment.

FIG. 19 is a flowchart showing a computation flow of a power reduction determining section in the second embodiment.

FIG. 20 is a diagram showing a modification of the driving system in the second embodiment.

FIG. 21 is a diagram showing a configuration of a driving system in a third embodiment.

FIG. 22 is a diagram showing a configuration of an operation signal system of the driving system in the third embodiment.

FIG. 23 is a diagram showing relation between inclinations in forward and rearward directions of a lever and the target rotation speed of an electric motor in the third embodiment.

FIG. 24 is a block diagram showing functions of a controller in the third embodiment.

FIG. 25 is a diagram of assistance in explaining conversion processing performed by a sensor signal converting section in the third embodiment.

FIG. 26 is a block diagram showing functions of a power computing section in the third embodiment.

FIG. 27 is a flowchart showing a computation flow of a first lever operation state determining section in the third embodiment.

FIG. 28 is a flowchart showing a computation flow of a second lever operation state determining section in the third embodiment.

MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will hereinafter be described according to the drawings.

First Embodiment

A first embodiment of the present invention will be described with reference to FIGS. 1 to 13.

Configuration

Description will first be made of a hydraulic excavator as a typical example of a construction machine in the first embodiment of the present invention.

FIG. 1 is a diagram showing an external appearance of a hydraulic excavator in the present embodiment.

The hydraulic excavator includes a lower track structure 101, an upper swing structure 102 swingably mounted on the lower track structure, and a swing type front work implement 104 attached to a front portion of the upper swing structure so as to be rotatable in an upward-downward direction. The front work implement 104 includes a boom 111, an arm 112, and a bucket 113. The upper swing structure 102 and the lower track structure 101 are rotatably connected to each other by a swing wheel 215. The upper swing structure 102 is swingable with respect to the lower track structure 101 by rotation of a swing motor 43. A swing post 103 is attached to a front portion of the upper swing structure 102. The front work implement 104 is attached to the swing post 103 so as to be vertically movable. The swing post 103 is rotatable with respect to the upper swing structure 102 in a horizontal direction by expansion and contraction of a swing cylinder (not shown). The boom 111, the arm 112, and the bucket 113 of the front work implement 104 are rotatable in the upward-downward direction by expansion and contraction of a boom cylinder 13, an arm cylinder 23, and a bucket cylinder 33 as front implement actuators. Attached to a central frame of the lower track structure 101 are a right and a left track device 105 a and 105 b and a blade 106 that moves up and down according to expansion and contraction of a blade cylinder 3 h. The right and left track devices 105 a and 105 b include driving wheels 210 a and 210 b, idlers 211 a and 211 b, and crawlers 212 a and 212 b, respectively. The right and left track devices 105 a and 105 b travel by transmitting rotation of a right and a left travelling motor 3 f and 3 g to the driving wheels 210 a and 210 b, and thereby driving the crawlers 212 a and 212 b.

A cabin 110 in which a cab 108 is formed is installed on the upper swing structure 102. The cab 108 is provided with a cab seat 122 and a right and a left control lever device 114 and 134 that instruct driving of the boom cylinder 13, the arm cylinder 23, the bucket cylinder 33, and the swing motor 43.

Description will next be made of a driving system included in the construction machine (hydraulic excavator) according to the present embodiment. FIG. 2 is a diagram showing a configuration of the driving system according to the present embodiment.

In FIG. 2, the driving system includes an engine 6 (diesel engine) as well as a main hydraulic pump 1 and a pilot pump 51. The hydraulic pump 1 and the pilot pump 51 are driven by the engine 6. The hydraulic pump 1 is connected to a line 2. A relief valve 3 is attached to the line 2 via a relief line 4. The downstream side of the relief valve 3 is connected to a tank 5. A tandem line 8 and a parallel line 9 are connected to the downstream of the line 2. Lines 11, 21, 31, and 41 are connected in parallel to the parallel line 9. Check valves 10, 20, 30, and 40 are arranged on the lines 11, 21, 31, and 41, respectively.

A directional control valve 12 is connected downstream of the line 8 and the line 11. The directional control valve 12 is also connected with a bottom line 13B connected to a bottom side chamber of the boom cylinder 13, a rod line 13R connected to a rod side chamber of the boom cylinder 13, a tank line 13T connected to the tank 5, and a center bypass line 13C.

The directional control valve 12 is driven by the pressure of a pilot line 12 b and the pressure of a pilot line 12 r. When the pressures of both of the pilot lines are low, the directional control valve 12 is at a neutral position so that the line 8 is connected to the center bypass line 13C and the other lines are interrupted. When the pressure of the pilot line 12 b is high, the directional control valve 12 is switched upward in the figure so that the line 11 is connected to the bottom line 13B, the tank line 13T is connected to the rod line 13R, and the line 8 and the center bypass line 13C are interrupted. When the pressure of the pilot line 12 r is high, the directional control valve 12 is switched downward in the figure so that the line 11 is connected to the rod line 13R, the tank line 13T is connected to the bottom line 13B, and the line 8 and the center bypass line 13C are interrupted.

A directional control valve 22 is connected downstream of the line 13C and the line 21. The directional control valve 22 is also connected with a bottom line 23B connected to a bottom side chamber of the arm cylinder 23, a rod line 23R connected to a rod side chamber of the arm cylinder 23, a tank line 23T connected to the tank 5, and a center bypass line 23C.

The directional control valve 22 is driven by the pressure of a pilot line 22 b and the pressure of a pilot line 22 r. When the pressures of both of the pilot lines are low, the directional control valve 22 is at a neutral position so that the center bypass line 13C is connected to the center bypass line 23C and the other lines are interrupted. When the pressure of the pilot line 22 b is high, the directional control valve 22 is switched upward in the figure so that the line 21 is connected to the bottom line 23B, the tank line 23T is connected to the rod line 23R, and the center bypass line 13C and the center bypass line 23C are interrupted. When the pressure of the pilot line 22 r is high, the directional control valve 22 is switched downward in the figure so that the line 21 is connected to the rod line 23R, the tank line 23T is connected to the bottom line 23B, and the center bypass line 13C and the center bypass line 23C are interrupted.

A directional control valve 32 is connected downstream of the line 23C and the line 31. The directional control valve 32 is also connected with a bottom line 33B connected to a bottom side chamber of the bucket cylinder 33, a rod line 33R connected to a rod side chamber of the bucket cylinder 33, a tank line 33T connected to the tank 5, and a center bypass line 33C.

The directional control valve 32 is driven by the pressure of a pilot line 32 b and the pressure of a pilot line 32 r. When the pressures of both of the pilot lines are low, the directional control valve 32 is at a neutral position so that the center bypass line 23C is connected to the center bypass line 33C and the other lines are interrupted. When the pressure of the pilot line 32 b is high, the directional control valve 32 is switched upward in the figure so that the line 31 is connected to the bottom line 33B, the tank line 33T is connected to the rod line 33R, and the center bypass line 23C and the center bypass line 33C are interrupted. When the pressure of the pilot line 32 r is high, the directional control valve 32 is switched downward in the figure so that the line 31 is connected to the rod line 33R, the tank line 33T is connected to the bottom line 33B, and the center bypass line 23C and the center bypass line 33C are interrupted.

A directional control valve 42 is connected downstream of the line 33C and the line 41. The directional control valve 42 is also connected with a left rotation line 43L connected to a left rotation side chamber of the swing motor 43, a right rotation line 43R connected to a right rotation side chamber of the swing motor 43, a tank line 43T connected to the tank 5, and a center bypass line 43C. The center bypass line 43C is connected to the tank 5.

The directional control valve 42 is driven by the pressure of a pilot line 42 l and the pressure of a pilot line 42 r. When the pressures of both of the pilot lines are low, the directional control valve 42 is at a neutral position so that the center bypass line 33C is connected to the center bypass line 43C and the other lines are interrupted. When the pressure of the pilot line 42 l is high, the directional control valve 42 is switched upward in the figure so that the line 41 is connected to the left rotation line 43L, the tank line 43T is connected to the right rotation line 43R, and the center bypass line 33C and the center bypass line 43C are interrupted. When the pressure of the pilot line 42 r is high, the directional control valve 42 is switched downward in the figure so that the line 41 is connected to the right rotation line 43R, the tank line 43T is connected to the left rotation line 43L, and the center bypass line 33C and the center bypass line 43C are interrupted.

The pilot pump 51 is connected to a pilot line 52. The downstream of the pilot line 52 will be described later with reference to FIG. 4.

Incidentally, though not shown, the hydraulic drive system has similar directional control valves provided also for the travelling motors 3 f and 3 g and the blade cylinder 3 h shown in FIG. 1 and the swing cylinder not shown in the figure so that the connection and interruption of lines can be performed.

Here, the engine 6 and the hydraulic pump 1 constitute a power source, and the boom cylinder 13, the arm cylinder 23, the bucket cylinder 33, and the swing motor 43 constitute a plurality of actuators that are actuated by receiving power output by the power source. The control lever devices 114 and 134 include a right and a left control lever 14 and 34 (first and second control levers) that each instruct amounts of power to be distributed to the plurality of actuators. The directional control valves 12, 22, 32, and 42 distribute power to the plurality of actuators on the basis of the instructions of the control levers 14 and 34.

A configuration of an operation signal system of a driving system will next be described with reference to FIG. 3 and FIG. 4.

FIG. 3 is a diagram of assistance in explaining movable directions of the control levers of the control lever devices 114 and 134 in the first embodiment and definitions of the movable directions.

As described with reference to FIG. 1, the right and left control lever devices 114 and 134 are installed in the cab 108 of the hydraulic excavator. An operator operates a control lever 14 (first control lever) of the control lever device 114 with a right hand, and operates a control lever 34 (second control lever) of the control lever device 134 with a left hand. The control lever devices 114 and 134 each allow two actuators to be operated by one control lever 14 or 34. The control levers 14 and 34 can each be operated from a neutral position. Operations of the control lever 14 in a forward direction 14 b and a rearward direction 14 r correspond to operations of boom lowering and boom raising of the boom cylinder 13. Operations of the control lever 14 in a right direction 24 r and a left direction 24 b correspond to operations of bucket dumping and bucket crowding of the bucket cylinder 33. Operations of the control lever 34 in a right direction 34 b and a left direction 34 r correspond to operations of arm crowding and arm dumping of the arm cylinder 23. Operations of the control lever 34 in a forward direction 44 l and a rearward direction 44 r correspond to operations of right swinging and left swinging of the swing motor 43. Incidentally, the forward direction, the rearward direction, the right direction, and the left direction in the present specification refer to a front direction, a rear direction, a right direction, and a left direction of the upper swing structure 102 as a machine body.

Thus, the control levers 14 and 34 of the control lever devices 114 and 134 can be operated in the plurality of directions from the neutral position, and operate different actuators among the plurality of actuators (the boom cylinder 13, the arm cylinder 23, the bucket cylinder 33, and the swing motor 43).

FIG. 4 is a diagram showing a configuration of an operation signal system of the driving system.

In FIG. 4, the control lever devices 114 and 134 are of a hydraulic pilot type, the control lever device 114 includes pilot valves 15 b and 15 r for the boom and pilot valves 25 b and 25 r for the bucket, the pilot valves 15 b and 15 r and the pilot valves 25 b and 25 r driven by the control lever 14, and the control lever device 134 includes pilot valves 35 b and 35 r for the arm and pilot valves 45 l and 45 r for swinging, the pilot valves 35 b and 35 r and the pilot valves 45 l and 45 r driven by the control lever 34. In the following description, the control levers may be referred to simply as “levers.”

Lines 19, 29, 39, and 49 and a relief valve 53 are connected in parallel with each other downstream of the pilot line 52. The tank 5 is connected downstream of the relief valve 53. The lines 19, 29, 39, and 49 are provided with restricting sections 94, 95, 96, and 97, respectively.

The pilot valve 15 b of the control lever device 114 is connected to the line 19, and is connected to a line 18 and a line 16 b. The line 16 b is connected to the pilot line 12 b (see FIG. 2). A pressure sensor 17 b is attached onto the line 16 b. The line 18 is connected to the tank 5.

When the lever 14 is at the neutral position, the pilot valve 15 b connects the line 18 and the line 16 b to each other, and interrupts the line 19. When the lever 14 is operated in the forward direction 14 b, the pilot valve 15 b connects the line 19 and the line 16 b to each other, and interrupts the line 18. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever 14 is generated in the line 16 b.

The pressure sensor 17 b measures the pressure of the line 16 b, and transmits a signal of the pressure of the line 16 b to a controller 50 electrically connected to the pressure sensor 17 b.

The pilot valve 15 r of the control lever device 114 is connected to the line 19, and is connected to the line 18 and a line 16 r. The line 16 r is connected to the pilot line 12 r (see FIG. 2). A pressure sensor 17 r is attached onto the line 16 r. The line 18 is connected to the tank 5.

When the lever 14 is at the neutral position, the pilot valve 15 r connects the line 18 and the line 16 r to each other, and interrupts the line 19. When the lever 14 is operated in the rearward direction 14 r, the pilot valve 15 r connects the line 19 and the line 16 r to each other, and interrupts the line 18. At this time, a pressure corresponding to an operation amount of the lever 14 is generated in the line 16 r.

The pressure sensor 17 r measures the pressure of the line 16 r, and transmits a signal of the pressure of the line 16 r to the controller 50 electrically connected to the pressure sensor 17 r.

The pilot valve 25 b of the control lever device 114 is connected to the line 29, and is connected to a line 28 and a line 26 b. The line 26 b is connected to the pilot line 32 b (see FIG. 2). A pressure sensor 27 b is attached onto the line 26 b. The line 28 is connected to the tank 5.

When the lever 14 is at the neutral position, the pilot valve 25 b connects the line 28 and the line 26 b to each other, and interrupts the line 29. When the lever 14 is operated in the left direction 24 b, the pilot valve 25 b connects the line 29 and the line 26 b to each other, and interrupts the line 28. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever 14 is generated in the line 26 b.

The pressure sensor 27 b measures the pressure of the line 26 b, and transmits a signal of the pressure of the line 26 b to the controller 50 electrically connected to the pressure sensor 27 b.

The pilot valve 25 r of the control lever device 114 is connected to the line 29, and is connected to the line 28 and a line 26 r. The line 26 r is connected to the pilot line 32 r (see FIG. 2). A pressure sensor 27 r is attached onto the line 26 r. The line 28 is connected to the tank 5.

When the lever 14 is at the neutral position, the pilot valve 25 r connects the line 28 and the line 26 r to each other, and interrupts the line 29. When the lever 14 is operated in the right direction 24 r, the pilot valve 25 r connects the line 29 and the line 26 r to each other, and interrupts the line 28. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever 14 is generated in the line 26 r.

The pressure sensor 27 r measures the pressure of the line 26 r, and transmits a signal of the pressure of the line 26 r to the controller 50 electrically connected to the pressure sensor 27 r.

The pilot valve 35 b of the control lever device 134 is connected to the line 39, and is connected to a line 38 and a line 36 b. The line 36 b is connected to the pilot line 22 b (see FIG. 2). A pressure sensor 37 b is attached onto the line 36 b. The line 38 is connected to the tank 5.

When the lever 34 is at the neutral position, the pilot valve 35 b connects the line 38 and the line 36 b to each other, and interrupts the line 39. When the lever 34 is operated in the right direction 34 b, the pilot valve 35 b connects the line 39 and the line 36 b to each other, and interrupts the line 38. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever 34 is generated in the line 36 b.

The pressure sensor 37 b measures the pressure of the line 36 b, and transmits a signal of the pressure of the line 36 b to the controller 50 electrically connected to the pressure sensor 37 b.

The pilot valve 35 r of the control lever device 134 is connected to the line 39, and is connected to the line 38 and a line 36 r. The line 36 r is connected to the pilot line 22 r (see FIG. 2). A pressure sensor 37 r is attached onto the line 36 r. The line 38 is connected to the tank 5.

When the lever 34 is at the neutral position, the pilot valve 35 r connects the line 38 and the line 36 r to each other, and interrupts the line 39. When the lever 34 is operated in the left direction 34 r, the pilot valve 35 r connects the line 39 and the line 36 r to each other, and interrupts the line 38. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever 34 is generated in the line 36 r.

The pressure sensor 37 r measures the pressure of the line 36 r, and transmits a signal of the pressure of the line 36 r to the controller 50 electrically connected to the pressure sensor 37 r.

The pilot valve 45 l of the control lever device 134 is connected to the line 49, and is connected to a line 48 and a line 46 l. The line 46 l is connected to the pilot line 42 l (see FIG. 2). A pressure sensor 47 l is attached onto the line 46 l. The line 48 is connected to the tank 5.

When the lever 34 is at the neutral position, the pilot valve 45 l connects the line 48 and the line 46 l to each other, and interrupts the line 49. When the lever 34 is operated in the forward direction 44 l, the pilot valve 45 l connects the line 49 and the line 46 l to each other, and interrupts the line 48. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever 34 is generated in the line 46 l.

The pressure sensor 47 l measures the pressure of the line 46 l, and transmits a signal of the pressure of the line 46 l to the controller 50 electrically connected to the pressure sensor 47 l.

The pilot valve 45 r of the control lever device 134 is connected to the line 49, and is connected to the line 48 and a line 46 r. The line 46 r is connected to the pilot line 42 r (see FIG. 2). A pressure sensor 47 r is attached onto the line 46 r. The line 48 is connected to the tank 5.

When the lever 34 is at the neutral position, the pilot valve 45 r connects the line 48 and the line 46 r to each other, and interrupts the line 49. When the lever 34 is operated in the rearward direction 44 r, the pilot valve 45 r connects the line 49 and the line 46 r to each other, and interrupts the line 48. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever 34 is generated in the line 46 r.

The pressure sensor 47 r measures the pressure of the line 46 r, and transmits a signal of the pressure of the line 46 r to the controller 50 electrically connected to the pressure sensor 47 r.

The pressure sensors 17 b, 17 r, 27 b, 27 r, 37 b, 37 r, 47 l, and 47 r constitute a plurality of operation state sensors that detect operation states of the control lever devices 114 and 134. In addition, the pressure sensors 17 b and 17 r constitute first operation state sensors that detect the operation state in a forward-rearward direction of the control lever 14. The pressure sensors 27 b and 27 r constitute second operation state sensors that detect the operation state in a right-left direction of the control lever 14. The pressure sensors 37 b and 37 r constitute third operation state sensors that detect the operation state in the right-left direction of the control lever 34. The pressure sensors 47 l and 47 r constitute fourth operation state sensors that detect the operation state in the forward-rearward direction of the control lever 34.

Incidentally, though not shown, the operation signal system has similar control lever devices provided also for the travelling motors 3 f and 3 g and the blade cylinder 3 h shown in FIG. 1 and the swing cylinder not shown. In the present embodiment, operation state sensors may be provided also for those control lever devices, and power reduction control to be described later may be performed on the basis of operation states of the control lever devices.

Returning to FIG. 2, the driving system according to the present embodiment further includes the controller 50 and a switch 76.

The controller 50 is electrically connected to the pressure sensors 17 b, 17 r, 27 b, 27 r, 37 b, 37 r, 47 l, and 47 r, the switch 76, and a target rotation speed indicating device 77. The controller 50 receives signals of respective measured pressures from the pressure sensors 17 b to 47 r, a signal from the switch 76, and a signal from the target rotation speed indicating device 77, computes a target rotation speed for the engine 6 on the basis of these signals, and transmits a command signal as a power command value to a rotation speed controller 7 of the engine 6, which is electrically connected to the controller 50. The rotation speed controller 7 controls the engine 6 so as to achieve the target rotation speed.

The switch 76 is a switch that selects whether to set a power reduction control mode by transmitting an ON or OFF signal to the controller 50. When the signal of the switch 76 is OFF, the power reduction control mode is canceled, and driving power of the engine 6 is not reduced even if all of the control levers are in a non-operation state.

Functions of the controller 50 in the first embodiment will next be described. FIG. 5 is a block diagram showing functions of the controller 50.

In FIG. 5, the controller 50 has respective functions of a sensor signal converting section 50 a, a constant and table storage section 50 b, and a power computing section 50 c.

The sensor signal converting section 50 a receives signals sent from the pressure sensors 17 b to 47 r and the switch 76, and converts the signals into pressure information and switch flag information. The sensor signal converting section 50 a transmits the converted pressure information and the converted switch flag information to the power computing section 50 c. Incidentally, the pressure information converted by the sensor signal converting section 50 a will be represented as sensor values P17 b(t), P17 r(t), P27 b(t), P27 r(t), P37 b(t), P37 r(t), P47 l(t), and P47 r(t), and the switch information converted by the sensor signal converting section 50 a will be represented as a switch flag Fsw(t). The pressure information converted by the sensor signal converting section 50 a is pressures generated in the lines 16 b to 46 r by driving the pilot valves 15 b to 45 r. The sensor values P17 b(t), P17 r(t), P27 b(t), P27 r(t), P37 b(t), P37 r(t), P47 l(t), and P47 r(t) may be referred to as “operation pressures.” In addition, suppose that Fsw(t)=true (enabled) when the switch 76 is ON, and that Fsw(t)=false (disabled) when the switch 76 is OFF.

The constant and table storage section 50 b stores constants and tables necessary for calculation. The constant and table storage section 50 b transmits these pieces of information to the power computing section 50 c.

The power computing section 50 c receives the pressure information and the switch flag information transmitted from the sensor signal converting section 50 a, target rotation speed information transmitted from the target rotation speed indicating device 77, and constant information and table information transmitted from the constant and table storage section 50 b, and computes the target rotation speed of the engine 6. Then, the power computing section 50 c outputs the target rotation speed to the rotation speed controller 7.

Functions of the power computing section 50 c in the first embodiment will next be described. FIG. 6 is a block diagram showing functions of the power computing section 50 c. Incidentally, suppose that a sampling time of the controller 50 is Δt.

In FIG. 6, the power computing section 50 c has respective functions of a first lever operation state determining section 50 c-1, a second lever operation state determining section 50 c-2, a first lever operation time measuring section 50 c-3, a second lever operation time measuring section 50 c-4, a power reduction determining section 50 c-5, and a delay element 50 c-6.

The first lever operation state determining section 50 c-1 determines whether the lever 14 is operated from the sensor values P17 b(t), P17 r(t), P27 b(t), and P27 r(t), and outputs a first lever non-operation flag F14(t). The first lever operation state determining section 50 c-1 sets the first lever non-operation flag F14(t) true when determining that the lever 14 is not operated. The first lever operation state determining section 50 c-1 sets the first lever non-operation flag F14(t) false when determining that the lever 14 is operated. This flag information is transmitted to the first lever operation time measuring section 50 c-3 and the power reduction determining section 50 c-5.

The second lever operation state determining section 50 c-2 determines whether the lever 34 is operated from the sensor values P37 b(t), P37 r(t), P47 l(t), and P47 r(t), and outputs a second lever non-operation flag F34(t). The second lever operation state determining section 50 c-2 sets the second lever non-operation flag F34(t) true when determining that the lever 34 is not operated. The second lever operation state determining section 50 c-2 sets the second lever non-operation flag F34(t) false when determining that the lever 34 is operated. This flag information is transmitted to the second lever operation time measuring section 50 c-4 and the power reduction determining section 50 c-5.

The first lever operation time measuring section 50 c-3 measures a first lever non-operation time Tu14(t) and a first lever operation time Tc14(t). These pieces of time information are transmitted to the power reduction determining section 50 c-5.

The second lever operation time measuring section 50 c-4 measures a second lever non-operation time Tu34(t) and a second lever operation time Tc34(t). These pieces of time information are transmitted to the power reduction determining section 50 c-5.

The power reduction determining section 50 c-5 determines whether to reduce the target rotation speed on the basis of the flag information F14(t) and F34(t), the time information Tu14(t), Tc14(t), Tu34(t), and Tc34(t), a power reduction flag F50(t−Δt) preceding by one step, the power reduction flag F50(t−Δt) being generated by the delay element 50 c-6, and the switch flag Fsw(t). The power reduction determining section 50 c-5 outputs the target rotation speed and a power reduction flag F50(t) from a result of the determination and the target rotation speed of the target rotation speed indicating device 77. The power reduction determining section 50 c-5 sets the power reduction flag F50(t) true when determining that the target rotation speed is to be reduced. The power reduction determining section 50 c-5 sets the power reduction flag F50(t) false when determining that the target rotation speed is not to be reduced.

Functions of the first lever operation state determining section 50 c-1 in the first embodiment will next be described. FIG. 7 is a flowchart showing a computation flow of the first lever operation state determining section 50 c-1 in FIG. 6. This computation flow is processed repeatedly in each sampling time Δt while the controller 50 operates, for example.

The computation of the first lever operation state determining section 50 c-1 is started in step S101.

In step S102, the first lever operation state determining section 50 c-1 determines whether the sensor value P17 b(t) is equal to or smaller than a threshold value Pth. When the sensor value P17 b(t) is equal to or less than the threshold value Pth, the first lever operation state determining section 50 c-1 determines Yes, and proceeds to the processing of step S103. When the sensor value P17 b(t) is larger than the threshold value Pth, the first lever operation state determining section 50 c-1 determines No, and proceeds to the processing of step S107.

In step S103, the first lever operation state determining section 50 c-1 determines whether the sensor value P17 r(t) is equal to or smaller than the threshold value Pth. When the sensor value P17 r(t) is equal to or smaller than the threshold value Pth, the first lever operation state determining section 50 c-1 determines Yes, and proceeds to the processing of step S104. When the sensor value P17 r(t) is larger than the threshold value Pth, the first lever operation state determining section 50 c-1 determines No, and proceeds to the processing of step S107.

In step S104, the first lever operation state determining section 50 c-1 determines whether the sensor value P27 b(t) is equal to or smaller than the threshold value Pth. When the sensor value P27 b(t) is equal to or smaller than the threshold value Pth, the first lever operation state determining section 50 c-1 determines Yes, and proceeds to the processing of step S105. When the sensor value P27 b(t) is larger than the threshold value Pth, the first lever operation state determining section 50 c-1 determines No, and proceeds to the processing of step S107.

In step S105, the first lever operation state determining section 50 c-1 determines whether the sensor value P27 r(t) is equal to or smaller than the threshold value Pth. When the sensor value P27 r(t) is equal to or smaller than the threshold value Pth, the first lever operation state determining section 50 c-1 determines Yes, and proceeds to the processing of step S106. When the sensor value P27 r(t) is larger than the threshold value Pth, the first lever operation state determining section 50 c-1 determines No, and proceeds to the processing of step S107.

In step S106, the first lever operation state determining section 50 c-1 determines that the lever 14 is not operated, and sets the first lever non-operation flag F14(t) true. Then, the first lever operation state determining section 50 c-1 transmits the flag information to the first lever operation time measuring section 50 c-3 and the power reduction determining section 50 c-5.

In step S107, the first lever operation state determining section 50 c-1 determines that the lever 14 is operated, and sets the first lever non-operation flag F14(t) false. Then, the first lever operation state determining section 50 c-1 transmits the flag information to the first lever operation time measuring section 50 c-3 and the power reduction determining section 50 c-5.

Functions of the second lever operation state determining section 50 c-2 in the first embodiment will next be described. FIG. 8 is a flowchart showing a computation flow of the second lever operation state determining section 50 c-2 in FIG. 6. This computation flow is processed repeatedly in each sampling time Δt while the controller 50 operates, for example.

The computation of the second lever operation state determining section 50 c-2 is started in step S201.

In step S202, the second lever operation state determining section 50 c-2 determines whether the sensor value P37 b(t) is equal to or smaller than the threshold value Pth. When the sensor value P37 b(t) is equal to or smaller than the threshold value Pth, the second lever operation state determining section 50 c-2 determines Yes, and proceeds to the processing of step S203. When the sensor value P37 b(t) is larger than the threshold value Pth, the second lever operation state determining section 50 c-2 determines No, and proceeds to the processing of step S207.

In step S203, the second lever operation state determining section 50 c-2 determines whether the sensor value P37 r(t) is equal to or smaller than the threshold value Pth. When the sensor value P37 r(t) is equal to or smaller than the threshold value Pth, the second lever operation state determining section 50 c-2 determines Yes, and proceeds to the processing of step S204. When the sensor value P37 r(t) is larger than the threshold value Pth, the second lever operation state determining section 50 c-2 determines No, and proceeds to the processing of step S207.

In step S204, the second lever operation state determining section 50 c-2 determines whether the sensor value P47 l(t) is equal to or smaller than the threshold value Pth. When the sensor value P47 l(t) is equal to or smaller than the threshold value Pth, the second lever operation state determining section 50 c-2 determines Yes, and proceeds to the processing of step S205. When the sensor value P47 l(t) is larger than the threshold value Pth, the second lever operation state determining section 50 c-2 determines No, and proceeds to the processing of step S207.

In step S205, the second lever operation state determining section 50 c-2 determines whether the sensor value P47 r(t) is equal to or smaller than the threshold value Pth. When the sensor value P47 r(t) is equal to or smaller than the threshold value Pth, the second lever operation state determining section 50 c-2 determines Yes, and proceeds to the processing of step S206. When the sensor value P47 r(t) is larger than the threshold value Pth, the second lever operation state determining section 50 c-2 determines No, and proceeds to the processing of step S207.

In step S206, the second lever operation state determining section 50 c-2 determines that the lever 34 is not operated, and sets the second lever non-operation flag F34(t) true. Then, the second lever operation state determining section 50 c-2 transmits the flag information to the second lever operation time measuring section 50 c-4 and the power reduction determining section 50 c-5.

In step S207, the second lever operation state determining section 50 c-2 determines that the lever 14 is operated, and sets the second lever non-operation flag F34(t) false. Then, the second lever operation state determining section 50 c-2 transmits the flag information to the second lever operation time measuring section 50 c-4 and the power reduction determining section 50 c-5.

A definition of the threshold value Pth for the above-described sensor values will be described with reference to FIG. 9. FIG. 9 shows relation between the sensor value P17 b(t) or P17 r(t) and the meter-in opening area of the directional control valve 12. In addition, the sensor value P17 b(t) or P17 r(t) is represented as an “operation pressure.”

In FIG. 9, until the operation pressure P17 b(t) or P17 r(t) becomes the value of Pth, a meter-in opening does not open, and therefore the hydraulic cylinder (boom cylinder) 13 is not actuated. This relation is the same for the other directional control valves. The operation state determining sections 50 c-1 and 50 c-2 use the pressure value Pth at which the meter-in opening opens as a threshold value.

Functions of the first lever operation time measuring section 50 c-3 in the first embodiment will next be described. FIG. 10 is a flowchart showing a computation flow of the first lever operation time measuring section 50 c-3 in FIG. 6. This computation flow is processed repeatedly in each sampling time Δt while the controller 50 operates, for example.

The computation of the first lever operation time measuring section 50 c-3 is started in step S301.

In step S302, the first lever operation time measuring section 50 c-3 determines whether the first lever non-operation flag F14(t) is true. When the first lever non-operation flag F14(t) is true, the first lever operation time measuring section 50 c-3 determines Yes, and proceeds to the processing of step S303. When the first lever non-operation flag F14(t) is false, the first lever operation time measuring section 50 c-3 determines No, and proceeds to the processing of step S304.

In step S303, since the lever 14 is not operated, the first lever operation time measuring section 50 c-3 sets, as a new first lever non-operation time Tu14(t), a value obtained by adding a sampling time Δt to a first lever non-operation time Tu14(t−Δt) preceding by one step. In addition, the first lever operation time measuring section 50 c-3 sets the first lever operation time Tc14(t) to zero. The first lever operation time measuring section 50 c-3 then transmits these pieces of information to the power reduction determining section 50 c-5.

In step S304, since the lever 14 is operated, the first lever operation time measuring section 50 c-3 sets the first lever non-operation time Tu14(t) to zero. In addition, the first lever operation time measuring section 50 c-3 sets, as a new first lever operation time Tc14(t), a value obtained by adding a sampling time Δt to a first lever operation time Tc14(t−Δt) preceding by one step. The first lever operation time measuring section 50 c-3 then transmits these pieces of information to the power reduction determining section 50 c-5.

Functions of the second lever operation time measuring section 50 c-4 in the first embodiment will next be described. FIG. 11 is a flowchart showing a computation flow of the second lever operation time measuring section 50 c-4 in FIG. 6. This computation flow is processed repeatedly in each sampling time Δt while the controller 50 operates, for example.

The computation of the second lever operation time measuring section 50 c-4 is started in step S401.

In step S402, the second lever operation time measuring section 50 c-4 determines whether the second lever non-operation flag F34(t) is true. When the second lever non-operation flag F34(t) is true, the second lever operation time measuring section 50 c-4 determines Yes, and proceeds to the processing of step S403. When the second lever non-operation flag F34(t) is false, the second lever operation time measuring section 50 c-4 determines No, and proceeds to the processing of step S404.

In step S403, since the lever 34 is not operated, the second lever operation time measuring section 50 c-4 sets, as a new second lever non-operation time Tu34(t), a value obtained by adding a sampling time Δt to a second lever non-operation time Tu34(t−Δt) preceding by one step. In addition, the second lever operation time measuring section 50 c-4 sets the second lever operation time Tc34(t) to zero. The second lever operation time measuring section 50 c-4 then transmits these pieces of information to the power reduction determining section 50 c-5.

In step S404, since the lever 34 is operated, the second lever operation time measuring section 50 c-4 sets the second lever non-operation time Tu34(t) to zero. In addition, the second lever operation time measuring section 50 c-4 sets, as a new second lever operation time Tc34(t), a value obtained by adding a sampling time Δt to a second lever operation time Tc34(t−Δt) preceding by one step. The second lever operation time measuring section 50 c-4 then transmits these pieces of information to the power reduction determining section 50 c-5.

Functions of the power reduction determining section 50 c-5 in the first embodiment will next be described. FIG. 12 is a flowchart showing a computation flow of the power reduction determining section 50 c-5 in FIG. 6. This computation flow is processed repeatedly in each sampling time Δt while the controller 50 operates, for example.

The computation of the power reduction determining section 50 c-5 is started in step S501.

In step S502, the power reduction determining section 50 c-5 determines whether the switch flag Fsw(t) is true. When the switch flag Fsw(t) is true, the power reduction determining section 50 c-5 determines Yes, and proceeds to the processing of step S503. When the switch flag Fsw(t) is false, the power reduction determining section 50 c-5 determines No, and proceeds to the processing of step S515.

In step S503, the power reduction determining section 50 c-5 determines whether a smaller value of the first lever non-operation time Tu14(t) and the second lever non-operation time Tu34(t) is equal to or more than a first predetermined time Tth1 set in advance as a time for starting power reduction control. When the smaller value of the first lever non-operation time Tu14(t) and the second lever non-operation time Tu34(t) is equal to or more than the first predetermined time Tth1, the power reduction determining section 50 c-5 determines Yes, and proceeds to the processing of step S510. When the smaller value of the first lever non-operation time Tu14(t) and the second lever non-operation time Tu34(t) is smaller than the first predetermined time Tth1, the power reduction determining section 50 c-5 determines No, and proceeds to the processing of step S504. The first predetermined time Tth1 is 10 to 15 seconds, for example. Thus, when neither of the two levers 14 and 34 is operated, and the non-operation times Tu14(t) and Tu34(t) of the two levers 14 and 34 are equal to or more than the first predetermined time Tth1, the determination is Yes, and power reduction control is performed in step S510 (to be described later). In addition, when at least one of the levers 14 and 34 is operated, and the operated lever is returned to a neutral position in a state in which the power reduction control is not performed, the non-operation time(s) Tu14(t) and/or Tu34(t) is (are) zero. Therefore, the determination is No, and the power reduction determining section 50 c-5 proceeds to the processing of step S504. Further, when at least one of the levers 14 and 34 is operated in a state under the power reduction control, the non-operation time(s) Tu14(t) and/or Tu34(t) is (are) zero. Therefore, the determination is No, and the power reduction determining section 50 c-5 proceeds to the processing of step S504.

In step S504, the power reduction determining section 50 c-5 determines whether the power reduction flag F50(t−Δt) preceding by one step is true. When the power reduction flag F50(t−Δt) is true (when the power reduction control has been performed until now), the power reduction determining section 50 c-5 determines Yes, and proceeds to the processing of step S505. When the power reduction flag F50(t−Δt) is false (when the power reduction control has been canceled until now), the power reduction determining section 50 c-5 determines No, and proceeds to the processing of step S515 to continue the cancellation of the power reduction control (to be described later).

In step S505, the power reduction determining section 50 c-5 determines whether the first lever non-operation flag F14(t) is true. When the first lever non-operation flag F14(t) is true (when the lever 14 is not operated), the power reduction determining section 50 c-5 determines Yes, and proceeds to the processing of step S506. When the first lever non-operation flag F14(t) is false (when the lever 14 is operated), the power reduction determining section 50 c-5 determines No, and proceeds to the processing of step S508.

In step S506, the power reduction determining section 50 c-5 determines whether the second lever non-operation flag F34(t) is true. When the second lever non-operation flag F34(t) is true (when the lever 34 is not operated), the power reduction determining section 50 c-5 determines Yes, and proceeds to the processing of step S510 to perform the power reduction control (to be described later). When the second lever non-operation flag F34(t) is false (when the lever 34 is operated), the power reduction determining section 50 c-5 determines No, and proceeds to the processing of step S507.

In step S507, the power reduction determining section 50 c-5 determines whether the second lever operation time Tc34(t) is more than a second predetermined time Tth2 set in advance as a time for which operation can be considered to be performed with an intention of an operator. When Tc34(t) is more than the second predetermined time Tth2 (when the operation time of the lever 34 exceeds Tth2), the power reduction determining section 50 c-5 determines Yes in step S507, and proceeds to the processing of step S511 to cancel the power reduction control (to be described later). When Tc34(t) is equal to or less than the second predetermined time Tth2 (when the operation time of the lever 34 is less than Tth2), the power reduction determining section 50 c-5 determines No in step S507, and proceeds to the processing of step S512 to continue the power reduction control. The second predetermined time Tth2 is shorter than the first predetermined time Tth1, and is, for example, 2 to 3 seconds.

In step S508, the power reduction determining section 50 c-5 determines whether the second lever non-operation flag F34(t) is true. When the second lever non-operation flag F34(t) is true (when the lever 34 is not operated), the power reduction determining section 50 c-5 determines Yes, and proceeds to the processing of step S509. When the second lever non-operation flag F34(t) is false (when the lever 34 is operated), the power reduction determining section 50 c-5 determines No, and proceeds to the processing of step S515 to cancel the power reduction control (to be described later).

Here, a case where No is determined in step S508 is a case of satisfying a first cancellation condition in which a determination of No is made in both step S505 and step S508 and thus the first and second control levers 14 and 34 are operated simultaneously in a state in which power is reduced. In the present embodiment, the power reduction control is canceled when the first cancellation condition in which the first and second control levers 14 and 34 are operated simultaneously is thus satisfied.

In step S509, the power reduction determining section 50 c-5 determines whether the first lever operation time Tc14(t) is more than the second predetermined time Tth2. When the first lever operation time Tc14(t) is more than the second predetermined time Tth2 (when the operation time of the lever 14 exceeds Tth2), the power reduction determining section 50 c-5 determines Yes, and proceeds to the processing of step S513 to cancel the power reduction control (to be described later). When the first lever operation time Tc14(t) is equal to or less than the second predetermined time Tth2 (when the operation time of the lever 14 is less than Tth2), the power reduction determining section 50 c-5 determines No, and proceeds to the processing of step S514 to continue the power reduction control.

Here, a case where No is determined in step S506 and Yes is determined in step S507 and a case where No is determined in step S508 and Yes is determined in step S509 are each a case of satisfying a second cancellation condition in which one of the first and second control levers 14 and 34 is operated in a state in which power is reduced and the operation state of the one control lever be continued for the second predetermined time Tth2. In the present embodiment, even when the above-described first cancellation condition is not satisfied, the power reduction control is canceled when the second cancellation condition in which one of the first and second control levers 14 and 34 is operated and the operation state of the one control lever is continued for the second predetermined time Tth2 is satisfied.

In step S510, the power reduction determining section 50 c-5 sets the power reduction flag F50(t) true, and at the same time, the power reduction determining section 50 c-5 reduces the target rotation speed of the engine 6 from a normal target rotation speed indicated by the target rotation speed indicating device 77. Then, the power reduction determining section 50 c-5 transmits target rotation speed information to the rotation speed controller 7. The rotation speed controller 7 decreases the rotation speed of the engine 6 by reducing an amount of fuel supplied to the engine 6. Processing of the same contents as in step S510 is performed also in step S512 and step S514. The power reduction determining section 50 c-5 thus performs the power reduction control in step S510, step S512, and step S514.

In step S511, the power reduction determining section 50 c-5 sets the power reduction flag F50(t) false, and at the same time, the power reduction determining section 50 c-5 sets the target rotation speed of the engine 6 to the normal value indicated by the target rotation speed indicating device 77. Then, the power reduction determining section 50 c-5 transmits target rotation speed information to the rotation speed controller 7. The rotation speed controller 7 increases the rotation speed of the engine 6 by increasing the amount of fuel supplied to the engine 6. Processing of the same contents as in step S511 is performed also in step S513 and step S515. The power reduction determining section 50 c-5 thus cancels the power reduction control in steps S511 and S513. In addition, in step S515, the power reduction determining section 50 c-5 continues the cancellation of the power reduction control when the power reduction control has not been performed until now, and the power reduction determining section 50 c-5 cancels the power reduction control when the power reduction control has been performed until now.

An example of changes in operation pressures and the target rotation speed in the first embodiment will next be described with reference to FIG. 13. FIG. 13 is a timing diagram showing an example of changes in operation pressures and the target rotation speed when the levers 14 and 34 are operated. An upper graph in FIG. 13 indicates temporal changes in the operation pressure P17 b(t) by the lever 14. A central graph indicates temporal changes in the operation pressure P37 b(t) by the lever 34. A lower graph indicates temporal changes in the target rotation speed. An axis of abscissas in all of the graphs indicates time (seconds). In addition, the operation pressure threshold value Pth is also provided in the upper graph and the central graph.

At time t0, the lever 14 is operated in the forward direction 14 b, and the lever 34 is operated in the right direction 34 b. Therefore, the pressure values of both the operation pressure P17 b(t) and the operation pressure P37 b(t) exceed the threshold value Pth. The pressure values of the other operation pressures not shown in the figure are zero. At this time, the processing of step S515 in FIG. 12 is performed (S502→S503→S504→S515), and the target rotation speed is thereby a normal value Nh indicated by the target rotation speed indicating device 77. That is, the power reduction control (auto idle control) is canceled.

From time t0 to time t1, the operation pressures P17 b(t) and P37 b(t) are both larger than the threshold value Pth. Also in this case, the processing of step S515 in FIG. 12 is performed (S502→S503→S504→S515), and the target rotation speed is thereby the normal value Nh.

At time t1, the levers 14 and 34 are returned to the neutral position, and both of the operation pressures P17 b(t) and P37 b(t) are a value smaller than the threshold value Pth. Therefore, the processing of step S515 is performed until after the seconds of the first predetermined time Tth1 from time t1. The processing of step S510 in FIG. 12 is thereafter performed (S502→S503→S510), thus the target rotation speed is reduced from the normal value Nh, and is set to a small value N1 of the power reduction control (auto idle control).

At time t2, the lever 34 is operated, and only the operation pressure P37 b(t) is higher than the threshold value Pth. At this time, the processing of step S512 in FIG. 12 is performed (S502→S503→S504→S505→S506→S507→S512), and the power reduction control is continued. When this state is continued for the seconds of the second predetermined time Tth2 or more, and the above-described second cancellation condition is satisfied, the processing of step S511 in FIG. 12 is performed (S502→S503→S504→S505→S506→S507→S511), thus the target rotation speed is set to the normal value Nh, and the power reduction control is canceled.

Incidentally, when the operation of the lever 34 at this time is an accidental operation, and the lever 34 is returned to the neutral position before reaching the seconds of the second predetermined time Tth2, the non-operation time Tu34(t) becomes zero. At this time, the determination in step S503 in FIG. 12 remains No, and the determination in step S506 becomes Yes. Therefore, the processing of step S510 is performed (S502→S503→S504→S505→S506→S510), thus the power reduction control is continued.

Thereafter, again at time t2 a, the operation pressure P37 b(t) decreases, and both of the operation pressures P17 b(t) and P37 b(t) become a value smaller than the threshold value Pth. When this state is continued for the seconds of the first predetermined time Tth1 or more, the processing of step S510 in FIG. 12 is performed (S502→S503→S510), thus the target rotation speed is set to the small value N1 of the power reduction control. Then, the operation pressures P17 b(t) and P37 b(t) simultaneously become higher than the threshold value Pth at time t3. At this time, the above-described first cancellation condition is satisfied, and the processing of step S515 in FIG. 12 is performed (S502→S503→S504→S505→S508→S515), thus the target rotation speed is set to the normal value Nh again without delay, and the power reduction control is canceled.

As described above, according to the present embodiment, the controller 50 determines, when the first cancellation condition in which the two control levers 14 and 34 of the respective control lever devices 114 and 134 are operated simultaneously in a power reduction state of the engine 6 and the hydraulic pump 1 is satisfied (S502→S503→S504→S505→S508→S515 in FIG. 12), that the “operator has an intention of canceling power reduction,” and cancels the power reduction control. Thus, while the power reduction control is performed during the non-operation of the two control levers 14 and 34, the power reduction control can be canceled by merely operating the two control levers 14 and 34 simultaneously in the power reduction state. In addition, since the power reduction control is canceled by merely operating the two control levers 14 and 34 simultaneously in the power reduction state, a smooth transition to an operation desired to be performed can be made at a time of a return to a normal power state.

On the other hand, when one control lever is operated, and the second cancellation condition in which one control lever is operated for a longer time than the second predetermined time Tth2 is satisfied, the power reduction control is canceled (S502→S503→S504→S505→S506→S507→S511 or S502→S503→S504→S505→S508→S509→S513). Thus, when one certain control lever is accidentally operated for a short time (time equal to or less than the second predetermined time Tth2), the power reduction control is not canceled, and a return to a normal power control state can be avoided. In addition, since the power reduction control is canceled by merely continuing operating one control lever for the second predetermined time Tth2 or more, a smooth transition to an operation desired to be performed can be made at a time of a return to the normal power state.

<First Modification>

In the first embodiment, as described above, the controller 50 is configured to cancel the power reduction control in each of a case where the two control levers 14 and 34 of the respective control lever devices 114 and 134 are operated simultaneously in the power reduction state of the engine 6 and the hydraulic pump 1 and a case where one control lever continues to be operated for the second predetermined time Tth2 or more. However, the controller 50 may be configured to cancel the power reduction control in only one of the cases, for example the case where the two control levers 14 and 34 of the respective control lever devices 114 and 134 are operated simultaneously in the power reduction state of the engine 6 and the hydraulic pump 1. Also in this case, it is possible to obtain effects of being able to perform the power reduction control during the non-operation of the control levers as described above, suppressing a return to the normal power state when a control lever is moved accidentally, and being able to make a smooth transition to an operation desired to be performed at a time of a return to the normal power state.

<Second Modification>

In the first embodiment, the controller 50 cancels, when the first cancellation condition in which the control levers 14 and 34 are operated simultaneously is satisfied, power limiting control even while the control lever 34 is operating the swing motor 43. However, the controller 50 may be configured not to cancel the power limiting control while the control lever 34 is operating the swing motor 43 even when the first cancellation condition in which the control levers 14 and 34 are operated simultaneously is satisfied, and to cancel the power reduction control only while the control lever 34 is not operating the swing motor 43.

Such a modification will be described with reference to FIG. 14 and FIG. 15.

FIG. 14 is a block diagram similar to FIG. 6, the block diagram showing functions of the power computing section 50 c of the controller 50 in the present embodiment.

In FIG. 14, the power computing section 50 c (see FIG. 5) includes a power reduction determining section 50 c-5D. The power reduction determining section 50 c-5D is supplied with the sensor values P47 l(t) and P47 r(t) of the pressure sensors 47 l and 47 r that detect the operation states in the forward and rearward directions of the control lever 34, which correspond to operation instructions for a right swing and a left swing of the swing motor 43, in addition to the first lever non-operation flag F14(t), the first lever non-operation time Tu14(t), the first lever operation time Tc14(t), the second lever non-operation flag F34(t), the second lever non-operation time Tu34(t), the second lever operation time Tc34(t), and the switch flag Fsw(t).

FIG. 15 is a flowchart showing a computation flow of the power reduction determining section 50 c-5D in FIG. 14.

In FIG. 15, step S530 is added to the computation flow of the power reduction determining section 50 c-5D. When the second lever non-operation flag F34(t) is false in step S508, the power reduction determining section 50 c-5D determines No, and proceeds to the processing of step S530.

In step S530, the power reduction determining section 50 c-5D determines whether the sensor value P47 l(t) is larger than the threshold value Pth and whether the sensor value P47 r(t) is larger than the threshold value Pth. Then, when the power reduction determining section 50 c-5D determines that one of the sensor value P47 l(t) and the sensor value P47 r(t) is larger than the threshold value Pth (when the control lever 34 operates the swing motor 43), the power reduction determining section 50 c-5D proceeds to the processing of step S514. When the power reduction determining section 50 c-5D determines that neither of the sensor value P47 l(t) and the sensor value P47 r(t) is larger than the threshold value Pth (when the control lever 34 is not operating the swing motor 43), the power reduction determining section 50 c-5D proceeds to the processing of step S515.

In step S514, the power reduction determining section 50 c-5D sets the power reduction flag F50(t) true, and at the same time, the power reduction determining section 50 c-5D reduces the target rotation speed of the engine 6 from the normal value indicated by the target rotation speed indicating device 77, and thereby performs the power reduction control. In step S515, the power reduction determining section 50 c-5D sets the power reduction flag F50(t) false, and at the same time, the power reduction determining section 50 c-5D sets the target rotation speed of the engine 6 to the normal value indicated by the target rotation speed indicating device 77.

Thus, in the present modification, when No is determined in step S508 and the first cancellation condition in which the first and second control levers 14 and 34 are operated simultaneously in a state in which power is reduced is satisfied, the power reduction control is canceled while No is determined in step S530 and the second control lever 34 is not operating the swing motor 43.

As with the first embodiment, the thus configured modification can suppress a return to the normal power state when a control lever is moved accidentally, enable a smooth transition to an operation desired to be performed at a time of a return to the normal power state, and prevent a degradation in operability when the two control levers 14 and 34 are operated simultaneously in order to cancel the power reduction control, because the upper swing structure 102 does not perform a swing operation.

<Third Modification>

In the first embodiment, description has been made of a case where the control lever devices 114 and 134 are of a hydraulic pilot type including pilot valves, and the operation state sensors are the pressure sensors 17 b, 17 r, 27 b, 27 r, 37 b, 37 r, 47 l, and 47 r that detect the operation pressures generated by the pilot valves. However, the operation state sensors may be of other configurations. For example, the operation states of the control lever devices may be detected by providing a signal pressure generating line that introduces the fluid delivered by the pilot pump 51 to the tank 5, arranging a plurality of signal pressure generating valves on the signal pressure generating line, switching the signal pressure generating valves by the operation pressures generated by the pilot valves, and detecting the pressure of the signal pressure generating line, which is changed by opening or closing the signal pressure generating valves. Also in this case, pressure sensors can detect the operation states of the control lever devices 114 and 134 as with the pressure sensors that detect the operation pressures, and effects similar to those of the first embodiment can be obtained.

Second Embodiment

A second embodiment of the present invention will be described with reference to FIGS. 16 to 19. Incidentally, description of the present embodiment will be made centering on parts different from those of the first embodiment, and description of parts similar to those of the first embodiment will be omitted.

A configuration of a driving system in the second embodiment will first be described. FIG. 16 is a diagram showing a configuration of a driving system in the present embodiment.

In FIG. 16, the driving system according to the second embodiment is different from that of the first embodiment in that the hydraulic pump 1 is driven by a direct-current electric motor 60A, in that the electric motor 60A is electrically connected to a battery 62, and the electric motor 60A is driven by electric power supplied from the battery 62, in that battery output power from the battery 62 is controlled by a battery output power control board 63, in that the battery output power control board 63 is electrically connected to a controller 50A, and in that the battery output power control board 63 controls the output electric power on the basis of target battery output power information transmitted from the controller 50A.

Here, the battery 62 is an electric power supply device, and this electric power supply device and the electric motor 60A constitute a power source.

Functions of the controller 50A in the second embodiment will next be described. FIG. 17 is a block diagram showing functions of the controller 50A.

In FIG. 17, the controller 50A in the second embodiment is different from that in the first embodiment in that the controller 50A includes a power computing section 50 cA in place of the power computing section 50 c, and the power computing section 50 cA receives the pressure information and the switch flag transmitted from the sensor signal converting section 50 a and the constant information and the table information transmitted from the constant and table storage section 50 b, and computes a target value of battery output power (target battery output power). The target battery output power computed by the power computing section 50 cA is transmitted to the battery output power control board 63. The battery output power control board 63 controls the output power of the battery 62 on the basis of the value.

Functions of the power computing section 50 cA in the second embodiment will next be described. FIG. 18 is a block diagram showing functions of the power computing section 50 cA.

In FIG. 18, the power computing section 50 cA in the second embodiment is different from that in the first embodiment in that the power computing section 50 cA includes a power reduction determining section 50 c-5A in place of the power reduction determining section 50 c-5 and in that the power reduction determining section 50 c-5A outputs the target battery output power. Inputs of the power reduction determining section 50 c-5A are the same as those of the power reduction determining section 50 c-5.

A computation flow of the power reduction determining section 50 c-5A in the second embodiment will next be described. FIG. 19 is a flowchart showing the computation flow of the power reduction determining section 50 c-5A.

In FIG. 19, the computation flow of the power reduction determining section 50 c-5A in the second embodiment is different from that in the first embodiment in that the processing of step S516 is performed in place of step S510, the processing of step S517 is performed in place of step S511, the processing of step S518 is performed in place of step S512, the processing of step S519 is performed in place of step S513, the processing of step S520 is performed in place of step S514, and the processing of step S521 is performed in place of step S515.

In step S516, the power reduction determining section 50 c-5A sets the power reduction flag F50(t) true, and at the same time, the power reduction determining section 50 c-5A reduces the target battery output power from that at a normal time. The power reduction determining section 50 c-5A then transmits the target battery output power to the battery output power control board 63. The same processing as in step S516 is performed also in step S518 and step S520.

In step S517, the power reduction determining section 50 c-5A sets the power reduction flag F50(t) false, and at the same time, the power reduction determining section 50 c-5A sets the target battery output power to a value at a normal time. The power reduction determining section 50 c-5A then transmits the target battery output power to the battery output power control board 63. The same processing as in step S517 is performed also in step S519 and step S521.

In the second embodiment configured as described above, also in a case where the power source is constituted by the battery 62 (electric power supply device), the electric motor 60A, and the hydraulic pump 1, as in the first embodiment, the controller 50 determines that the operator “has an intention of canceling power reduction” and cancels the power reduction control when the first cancellation condition in which the two control levers 14 and 34 of the respective control lever devices 114 and 134 are operated simultaneously in the power reduction state of the power source is satisfied or when the second cancellation condition in which one control lever continues to be operated for the second predetermined time Tth2 or more is satisfied. It is thereby possible to perform the power reduction control during the non-operation of the control levers, suppress a return to the normal power state when a control lever is accidentally moved, and make a smooth transition to an operation desired to be performed at a time of a return to the normal power state.

<Modification>

In the second embodiment, the power source of the driving system is constituted by the direct-current electric motor 60A and the hydraulic pump 1. However, an alternating-current electric motor may be used in place of the direct-current electric motor 60A. FIG. 20 is a diagram showing a modification of such a driving system.

In FIG. 20, the power source of the driving system is constituted by an alternating-current electric motor 60B and the hydraulic pump 1. The hydraulic pump 1 is driven by the alternating-current electric motor 60B. The electric motor 60B is controlled by an inverter 61. The inverter 61 is electrically connected to the controller 50. The inverter 61 receives information about the target rotation speed from the controller 50. The controller 50 computes the target rotation speed by performing processing similar to that of the controller 50 shown in FIG. 5. In addition, the inverter 61 is also electrically connected to the battery 62 from which the inverter 61 receives electric power to be supplied to the electric motor 60B. Such a configuration can also provide effects similar to those of the first and second embodiments.

Third Embodiment

A third embodiment of the present invention will be described with reference to FIGS. 21 to 28. The present embodiment performs power reduction by decreasing potential within a driving system.

A configuration of the driving system in the third embodiment will first be described. FIG. 21 is a diagram showing the configuration of the driving system in the present embodiment.

In FIG. 21, a controller 50C is electrically connected to an angle sensor 72, an angle sensor 73, an angle sensor 74, and an angle sensor 75 to be described later and a switch 76, and the controller 50C receives signals of angle information and switch information from these sensors 72 to 75 and the switch 76. The controller 50C computes the target battery output power of a battery 62 on the basis of these signals, and transmits target battery output power to a battery output power control board 63 electrically connected to the controller 50C. The battery output power control board 63 controls the battery 62 so as to provide the target battery output power.

The battery 62 is connected to a positive electrode side wire 81 and a negative electrode side wire 82. Inverters 83, 84, 85, and 86 are connected in parallel to the positive electrode side wire 81 and the negative electrode side wire 82.

The inverter 83 drives an electric motor 87. The electric motor 87 further drives a cylinder 91 (boom cylinder). The cylinder 91 performs expansion and contraction by converting a rotary motion of the electric motor 87 into a rectilinear motion by a rack-and-pinion mechanism or the like. The inverter 83 receives a signal transmitted from the angle sensor 72, and controls the electric motor 87 so as to achieve a rotation speed corresponding to the information of the signal.

The inverter 84 drives an electric motor 88. The electric motor 88 further drives a cylinder 92 (arm cylinder). The cylinder 92 performs expansion and contraction by converting a rotary motion of the electric motor 88 into a rectilinear motion by a rack-and-pinion mechanism or the like. The inverter 84 receives a signal transmitted from the angle sensor 73, and controls the electric motor 88 so as to achieve a rotation speed corresponding to the information of the signal.

The inverter 85 drives an electric motor 89. The electric motor 89 further drives a cylinder 93 (bucket cylinder). The cylinder 93 performs expansion and contraction by converting a rotary motion of the electric motor 89 into a rectilinear motion by a rack-and-pinion mechanism or the like. The inverter 85 receives a signal transmitted from the angle sensor 74, and controls the electric motor 89 so as to achieve a rotation speed corresponding to the information of the signal.

The inverter 86 drives an electric motor 90. The inverter 86 receives a signal transmitted from the angle sensor 75, and controls the electric motor 90 (swing motor) so as to achieve a rotation speed corresponding to the information of the signal.

Here, the battery 62 is an electric power supply device, and this electric power supply device constitutes a power source. In addition, the electric motor 87 and the cylinder 91, the electric motor 88 and the cylinder 92, the electric motor 89 and the cylinder 93, and the electric motor 90 constitute a plurality of actuators that are actuated by receiving power from the power source. The inverters 83, 84, 85, and 86 constitute power distributing devices that distribute the power to the plurality of actuators (the electric motor 87 and the cylinder 91, the electric motor 88 and the cylinder 92, the electric motor 89 and the cylinder 93, and the electric motor 90). Control lever devices 314 and 334 to be described later instruct the power distributing devices (inverters 83, 84, 85, and 86) about amounts of the power to be distributed to the plurality of actuators (the electric motor 88 and the cylinder 92, the electric motor 89 and the cylinder 93, and the electric motor 90).

A configuration of an operation signal system in the third embodiment will next be described with reference to FIG. 22 and FIG. 23.

FIG. 22 is a diagram showing the configuration of the operation signal system of the driving system in the third embodiment.

In FIG. 22, the operation signal system in the third embodiment is different from the operation signal system in the first embodiment, which is shown in FIG. 4, in that control lever devices in the third embodiment include the control lever device 314 in place of the control lever device 114, and include the control lever device 334 in place of the control lever device 134. The control lever devices 314 and 334 are of an electric lever type. The control lever device 314 includes a lever 14, an angle sensor 72 that outputs information about angles in a forward direction 14 b and a rearward direction 14 r, and an angle sensor 73 that outputs information about angles in a left direction 24 b and a right direction 24 r. The control lever device 334 includes an angle sensor 74 that outputs information about angles in a right direction 34 b and a left direction 34 r and an angle sensor 75 that outputs information about angles in a forward direction 44 l and a rearward direction 44 r.

The angle sensors 72, 73, 74, and 75 constitute a plurality of operation state sensors that detect the operation states of the control lever devices 314 and 334.

The angle sensors 72, 73, 74, and 75 are electrically connected to the controller 50C. The angle sensor 72 is also electrically connected to the inverter 83. The angle sensor 72 transmits the angle information to the inverter 83. The angle sensor 73 is also electrically connected to the inverter 85. The angle sensor 73 transmits the angle information to the inverter 85. The angle sensor 74 is also electrically connected to the inverter 84. The angle sensor 74 transmits the angle information to the inverter 84. The angle sensor 75 is also electrically connected to the inverter 86. The angle sensor 75 transmits the angle information to the inverter 86.

FIG. 23 is a diagram showing relation between inclinations in the forward and rearward directions 14 b and 14 r of the lever 14 and the target rotation speed of the electric motor 87. As shown in FIG. 23, as the lever 14 is inclined in the forward direction 14 b, the target rotation speed of the electric motor 87 is increased in a clockwise direction. In addition, the target rotation speed of the electric motor 87 is zero at a time of non-operation. As the lever 14 is inclined in the rearward direction 14 r, the target rotation speed of the electric motor 87 is increased in a counterclockwise direction.

Also when the lever 14 is inclined in the right direction 24 r or the left direction 24 b, and the lever 34 is inclined in the right direction 34 b or the left direction 34 r and in the forward direction 44 l or the rearward direction 44 r, the target rotation speeds of the electric motors 88, 89, and 90 similarly change.

Functions of the controller 50C in the third embodiment will next be described. FIG. 24 is a block diagram showing functions of the controller 50C.

In FIG. 24, the controller 50C in the third embodiment is different from that in the second embodiment in that the controller 50C in the third embodiment includes a sensor signal converting section 50 aC in place of the sensor signal converting section 50 a, and includes a power computing section 50 cC in place of the power computing section 50 cA.

The sensor signal converting section 50 aC receives signals sent from the angle sensors 72 to 75 and the switch 76, and converts the signals into angle information and switch flag information. The sensor signal converting section 50 aC transmits the converted angle information and the converted switch flag information to the power computing section 50 cC.

The constant and table storage section 50 b stores constants and tables necessary for computation. The constant and table storage section 50 b transmits the constants and the tables to the power computing section 50 cC.

The power computing section 50 cC receives the angle information and the switch flag information transmitted from the sensor signal converting section 50 aC and the constant information and the table information transmitted from the constant and table storage section 50 b, and computes the target battery output power of the battery 62. The power computing section 50 cC then outputs a target battery output power value to the battery output power control board 63. The battery output power control board 63 controls the output power of the battery 62 on the basis of the value.

Sensor signal conversion processing in the sensor signal converting section 50 aC will be described. FIG. 25 is a diagram of assistance in explaining the conversion processing performed by the sensor signal converting section 50 aC when the lever 14 is inclined in the forward direction 14 b or the rearward direction 14 r.

As shown in FIG. 25, the sensor signal converting section 50 aC performs conversion so that a sensor value A72(t) is increased as the lever 14 is inclined in the forward direction 14 b. In addition, the sensor signal converting section 50 aC performs conversion so that the sensor value A72(t) is zero at a time of non-operation. The sensor value A72(t) becomes a negative value when the lever 14 is inclined in the rearward direction 14 r. The same is true when the lever 14 is inclined in the right direction 24 r or the left direction 24 b, and when the lever 34 is inclined in the right direction 34 b or the left direction 34 r and in the forward direction 44 l or the rearward direction 44 r. The sensor value A72(t) is a value corresponding to the target rotation speed of the electric motor 87 in FIG. 23.

Functions of the power computing section 50 cC in the third embodiment will next be described. FIG. 26 is a block diagram showing functions of the power computing section 50 cC. Suppose that the sampling time of the controller 50C is Δt.

In FIG. 26, the power computing section 50 cC in the third embodiment is different from that in the first embodiment in that the power computing section 50 cC in the third embodiment includes a first lever operation state determining section 50 c-1C in place of the first lever operation state determining section 50 c-1, includes a second lever operation state determining section 50 c-2C in place of the second lever operation state determining section 50 c-2, and includes the same power reduction determining section 50 c-5C as in the second embodiment in place of the power reduction determining section 50 c-5.

Functions of the first lever operation state determining section 50 c-1C in the third embodiment will next be described. FIG. 27 is a flowchart showing a computation flow of the first lever operation state determining section 50 c-1C. This computation flow is processed repeatedly in each sampling time Δt while the controller 50 operates, for example.

The computation flow of the first lever operation state determining section 50 c-1C is different from the computation flow of the first lever operation state determining section 50 c-1 in the first embodiment, which is shown in FIG. 7, in that the processing from step S102 to step S105 is eliminated, and the computation flow of the first lever operation state determining section 50 c-1C proceeds from step S101 to the processing of step S110 and step S111.

In step S110, the first lever operation state determining section 50 c-1C determines whether the absolute value of the sensor value A72(t) is smaller than a threshold value Ath. When the absolute value of the sensor value A72(t) is smaller than the threshold value Ath, the first lever operation state determining section 50 c-1C determines Yes, and proceeds to the processing of step S111. When the absolute value of the sensor value A72(t) is equal to or larger than the threshold value Ath, the first lever operation state determining section 50 c-1C determines No, and proceeds to the processing of step S107.

In step S111, the first lever operation state determining section 50 c-1C determines whether the absolute value of a sensor value A73(t) is smaller than the threshold value Ath. When the absolute value of the sensor value A73(t) is smaller than the threshold value Ath, the first lever operation state determining section 50 c-1C determines Yes, and proceeds to the processing of step S106. When the absolute value of the sensor value A73(t) is equal to or larger than the threshold value Ath, the first lever operation state determining section 50 c-1C determines No, and proceeds to the processing of step S107.

In step S106, the first lever operation state determining section 50 c-1C sets the first lever non-operation flag F14(t) true. In step S107, the first lever operation state determining section 50 c-1C sets the first lever non-operation flag F14(t) false. These pieces of flag information are transmitted to the first lever operation time measuring section 50 c-3 and the power reduction determining section 50 c-5C.

Functions of the second lever operation state determining section 50 c-2C in the third embodiment will next be described. FIG. 28 is a flowchart showing a computation flow of the second lever operation state determining section 50 c-2C. This computation flow is processed repeatedly in each sampling time Δt while the controller 50 operates, for example.

The computation flow of the second lever operation state determining section 50 c-2C is different from the computation flow of the second lever operation state determining section 50 c-2 in the first embodiment, which is shown in FIG. 8, in that the processing from step S202 to step S205 is eliminated, and the computation flow of the second lever operation state determining section 50 c-2C proceeds from step S201 to the processing of step S210 and step S211.

In step S210, the second lever operation state determining section 50 c-2C determines whether the absolute value of a sensor value A74(t) is smaller than the threshold value Ath. When the absolute value of the sensor value A74(t) is smaller than the threshold value Ath, the second lever operation state determining section 50 c-2C determines Yes, and proceeds to the processing of step S211. When the absolute value of the sensor value A74(t) is equal to or larger than the threshold value Ath, the second lever operation state determining section 50 c-2C determines No, and proceeds to the processing of step S207.

In step S211, the second lever operation state determining section 50 c-2C determines whether the absolute value of a sensor value A75(t) is smaller than the threshold value Ath. When the absolute value of the sensor value A75(t) is smaller than the threshold value Ath, the second lever operation state determining section 50 c-2C determines Yes, and proceeds to the processing of step S206. When the absolute value of the sensor value A75(t) is equal to or larger than the threshold value Ath, the second lever operation state determining section 50 c-2C determines No, and proceeds to the processing of step S207.

In step S206, the second lever operation state determining section 50 c-2C sets the second lever non-operation flag F34(t) true. In step S207, the second lever operation state determining section 50 c-2C sets the second lever non-operation flag F34(t) false. These pieces of flag information are transmitted to the second lever operation time measuring section 50 c-4 and the power reduction determining section 50 c-5C.

Thus, the first lever operation state determining section 50 c-1C determines whether the lever 14 is operated from the sensor value A72(t) and the sensor value A73(t), and outputs the first lever non-operation flag F14(t). The second lever operation state determining section 50 c-2C determines whether the lever 34 is operated from the sensor value A74(t) and the sensor value A75(t), and outputs the second lever non-operation flag F34(t).

The first lever operation time measuring section 50 c-3 measures the first lever non-operation time Tu14(t) and the first lever operation time Tc14(t). These pieces of time information are transmitted to the power reduction determining section 50 c-5C.

The second lever operation time measuring section 50 c-4 measures the second lever non-operation time Tu34(t) and the second lever operation time Tc34(t). These pieces of time information are transmitted to the power reduction determining section 50 c-5C.

As with the power reduction determining section 50 c-5A in the second embodiment, the power reduction determining section 50 c-5A being shown in FIG. 18, the power reduction determining section 50 c-5C determines whether to reduce the battery output power according to the procedure of the flowchart shown in FIG. 19, and outputs the target battery output power and the power reduction flag F50(t). The target battery output power is transmitted to the battery output power control board 63. The battery output power control board 63 controls the battery 62 so as to provide the target battery output power.

In the third embodiment configured as described above, also in a case where the power source is constituted by the battery 62 (electric power supply device), and the actuators are constituted by electric actuators including the electric motors 87 to 90, as in the first embodiment, the controller 50 determines that the operator “has an intention of canceling power reduction” and cancels the power reduction control when the first cancellation condition in which the two control levers 14 and 34 of the respective control lever devices 314 and 334 are operated simultaneously in the power reduction state of the power source is satisfied or when the second cancellation condition in which one control lever continues to be operated for the second predetermined time Tth2 or more is satisfied. It is thereby possible to perform the power reduction control during the non-operation of the control levers, suppress a return to the normal power state when a control lever is accidentally moved, and make a smooth transition to an operation desired to be performed at a time of a return to the normal power state.

DESCRIPTION OF REFERENCE CHARACTERS

-   1: Hydraulic pump (power source) -   2: Line -   3: Relief valve -   4: Relief line -   5: Tank -   6: Engine (power source) -   7: Rotation speed controller -   8: Tandem line -   9: Parallel line -   10, 20, 30, 40: Check valve -   11, 21, 31, 41: Line -   12, 22, 32, 42: Directional control valve (power distributing     device) -   12 r, 12 b, 22 r, 22 b, 32 r, 32 b, 42 r, 42 l: Pilot line -   13, 23, 33: Cylinder (actuator) -   13B, 23B, 33B: Bottom line -   13R, 23R, 33R: Rod line -   13T, 23T, 33T, 43T: Tank line -   13C, 23C, 33C, 43C: Center bypass line -   14: Control lever (first control lever) -   15 r, 15 b, 25 r, 25 b, 35 r, 35 b, 45 r, 45 l: Pilot valve -   16 r, 16 b, 26 r, 26 b, 36 r, 36 b, 46 r, 46 l: Line -   17 r, 17 b, 27 r, 27 b, 37 r, 37 b, 47 l, 47 r: Pressure sensor     (operation state sensor) -   18, 28, 38, 48: Line -   19, 29, 39, 49: Line -   34: Control lever (second control lever) -   43: Hydraulic motor -   43L: Left rotation line -   43R: Right rotation line -   50: Controller -   51: Pilot pump -   52: Pilot line -   53: Relief valve -   60A: Electric motor (direct current) (power source) -   60B: Electric motor (alternating current) (power source) -   61: Inverter -   62: Battery (electric power supply device; power source) -   63: Battery output power control board -   72, 73, 74, 75: Angle sensor (operation state sensor) -   76: Switch -   81: Positive electrode side wire -   82: Negative electrode side wire -   83, 84, 85, 86: Inverter (power distributing device) -   87, 88, 89, 90: Electric motor (alternating current) (actuator) -   91, 92, 93: Cylinder (actuator) -   94, 95, 96, 97: Restricting section -   114, 134: Control lever device -   314, 334: Control lever device 

1. A construction machine comprising: a power source; a plurality of actuators that are actuated by receiving a power output by the power source; a plurality of control levers that instruct amounts of the power to be distributed to the plurality of actuators; a plurality of operation state sensors that detect operation states of the plurality of control levers; and a controller that controls the power source, the plurality of control levers including a first control lever and a second control lever that operate different actuators of the plurality of actuators, and the controller being configured to perform power reduction control of reducing the power when a non-operation state of the first and second control levers is continued, wherein the controller is configured to cancel the power reduction control when a first cancellation condition in which the first and second control levers are operated simultaneously in a state in which the power is reduced is satisfied.
 2. The construction machine according to claim 1, wherein the controller is configured to cancel the power reduction control when a second cancellation condition in which one of the first and second control levers is operated in a state in which the power is reduced and the operation state of the one control lever is continued for a predetermined time is satisfied even when the first cancellation condition is not satisfied.
 3. The construction machine according to claim 1, further comprising: a lower track structure; an upper swing structure swingably mounted on the lower track structure; and a front work implement attached to a front portion of the upper swing structure so as to be rotatable in an upward-downward direction, wherein the plurality of actuators include a swing motor that swings the upper swing structure with respect to the lower track structure, and first, second and third front implement actuators that drive the front work implement, the first control lever is a control lever that operates the first and second front implement actuators, and the second control lever is a control lever that operates the swing motor and the third front implement actuator, the plurality of operation state sensors include first operation state sensors that detect an operation state of the first control lever when the first control lever operates the first front implement actuator, second operation state sensors that detect an operation state of the first control lever when the first control lever operates the second front implement actuator, third operation state sensors that detect an operation state of the second control lever when the second control lever operates the third front implement actuator, and fourth operation state sensors that detect an operation state of the second control lever when the second control lever operates the swing motor, and the controller is configured to cancel the power reduction control on a basis of detection results of the first, second, third operation state sensors, and the fourth operation state sensor when the first cancellation condition in which the first and second control levers are operated simultaneously is satisfied and the second control lever is not operating the swing motor.
 4. The construction machine according to claim 1, wherein the power source includes an engine and a hydraulic pump, the power source generates the power by driving the hydraulic pump by the engine, and the controller is configured to perform the power reduction control by decreasing a rotation speed of the engine.
 5. The construction machine according to claim 1, wherein the power source includes an electric power supply device, an electric motor, and a hydraulic pump, the power source generates the power by driving the electric motor by electric power supply from the electric power supply device, and driving the hydraulic pump by the electric motor, and the controller is configured to perform the power reduction control by decreasing a rotation speed of the electric motor by reducing the electric power supply to the electric motor.
 6. The construction machine according to claim 1, wherein the power source includes an electric power supply device, the actuators are electric actuators including electric motors, the power source drives the electric actuators by electric power supply from the electric power supply device, and the controller is configured to perform the power reduction by decreasing rotation speeds of the electric motors by reducing electric power supplied from the electric power supply device to the electric motors. 